Marmalade's not bad, I used it in 2013. Some bugs, some annoyances (fixed memory pools), but overall not a bad experience.
The only real disappointment is the lack of support for Linux. I cannot see how the Marmalade guys can support obscure platforms like Blackberry, but not Linux; it makes no sense. Maybe this will change as Steam OS (a Linux-based, gaming-centric platform) matures, though admittedly Steam OS doesn't bring a whole lot to the table outside of what other OSs bring, for now.